Belgium is covered in a veil of fog… but how does it form?

The Royal Meteorological Institute issues a fog alert. It was already present this Wednesday and it will continue to cover almost the entire territory until 10 a.m. Thursday morning. Visibility will be limited in places to barely 200 meters. But where does this phenomenon come from?

It is a veil that settled this morning over our countryside and our towns and ultimately remained there all day. The fog covers everything, including the most imposing monuments.

“It is a slightly milder air which comes to us from the North Sea and therefore which also brings a little humidity. And this softness will finally fly over the soils which are still very cold and frozen following the fairly severe frosts of the previous days.“, explains Pascal Mormal, meteorologist at IRM.

Fog forms when cold ground meets warmer, more humid air. The vapor in the air condenses into water droplets, which can cause problems on the road. So it’s better to take precautions.

When we are driving and the fog falls, it is these microscopic water droplets that reduce our visibility. “As soon as we have these droplets in the air, they obstruct light. And so we can’t see well. And if we use our classic headlights, this light is reflected back into our faces. So there is no point in using conventional headlights. We are obliged to use fog lights which have a different color which improves visibility. Because this color passes through these small water droplets better“, explains Pasquale Nardone, professor of physics at the Free University of Brussels.

And these droplets will remain on the territory for several more days, at least until the end of the week, before disappearing when the sun returns.

fog weather mri